Activation of porphyrins with waves of different spectra: new possibilities in the treatment of malignant tumors

Abstract

We hypothesized that porphyrins in cancerous tissues can be activated not only by visible or ultraviolet light. Suitable wavelengths of ionizing radiation rays of a certain power are themselves capable of activating porphyrins. We have carried out experiments with hematoporphyrin derivative (HpD) solutions by activating them with visible light and γ rays from radioactive 60Co. On obtaining positive results with HpD solutions, in vivo experiments with C6 rat glioma were performed. In experiments with HpD solutions, when HpD concentration was adequate, during illumination of such solution with the blue light a crimson fluorescence was established. However, it disappeared when the solution underwent irradiation with γ rays (2 Gy). But if the solution was covered with soda-lime glass and exposed to irradiation with γ rays (2 Gy), the crimson fluorescence under illumination with the blue light was fixed again. Referring to our results, we may regard soda-lime glass as a filter which can eliminate the essential wavelength (or wavelengths) of the γ-ray spectrum capable of HpD activation. Detection of these wavelengths would enable researchers to find other ionizing radiation sources capable of activating some porphyrins more effectively. Keywords: sensitized tumor treatment, porphyrins, soda-lime glass